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Set CPU Affinity For A Ruby Script In Linux

04.23.2007
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require 'rubygems'
require 'inline'

# Oodles of inspiration and examples from
# http://www-128.ibm.com/developerworks/linux/library/l-affinity.html

class LinuxScheduler
  inline do |builder|
    builder.include '<sched.h>'
    builder.include '<stdio.h>'
    builder.c '
      int _set_affinity(int cpu_id) {
        cpu_set_t mask;
        __CPU_ZERO(&mask);
        __CPU_SET(cpu_id, &mask);
        if(sched_setaffinity(getpid(), sizeof(mask), &mask ) == -1) {
          printf("WARNING: Could not set CPU Affinity, continuing as-is\n");
          return 0;
        }
        return 1;
      }
    '
  end

  # cpu_id is 0-based, so for core/cpu 1 = 0, etc..
  def self.set_affinity(cpu_id)
    self.new._set_affinity(cpu_id.to_i)
  end
end


# Set this process's CPU affinity
LinuxScheduler.set_affinity(ARGV.first)

# Hog up all the CPU time on that processor
1000000.times { b = rand(100) ** 100 }